* fhandler.h (fhandler_cygdrive:DRVSZ): New enum.

(pdrive_buf): New place to hold information about cygdrive.
* fhandler_disk_file.cc (fhandler_cygdrive::set_drives): Store drive info in
pdrive_buf since get_win32_name() could now be too small to hold everything.
(fhandler_cygdrive::rewinddir): Reset pdrive to pdrive_buf.
(fhandler_cygdrive::closedir): Ditto.
* pipe.cc (fhandler_pipe::init): Be more defensive when referencing
get_win32_name().  Rework logic which made a copy of the POSIX path and then
never used it.

winsup/cygwin/fhandler.h

@@ -753,8 +753,13 @@ class fhandler_disk_file: public fhandler_base
 
 class fhandler_cygdrive: public fhandler_disk_file
 {
+  enum
+  {
+    DRVSZ = sizeof ("x:\\")
+  };
   int ndrives;
   const char *pdrive;
+  char pdrive_buf[2 * 26 * DRVSZ];
   void set_drives ();
  public:
   fhandler_cygdrive ();